// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_
#define NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_

#include <stdint.h>

#include <memory>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "net/base/net_export.h"

namespace net {

namespace der {
    class Input;
} // namespace der

// The digest algorithm used within a signature.
enum class DigestAlgorithm {
    Sha1,
    Sha256,
    Sha384,
    Sha512,
};

// The signature scheme used within a signature. Parameters are specified
// separately.
enum class SignatureAlgorithmId {
    RsaPkcs1, // RSA PKCS#1 v1.5
    RsaPss, // RSASSA-PSS
    Ecdsa, // ECDSA
};

// Parses a HashAlgorithm as defined by RFC 5912:
//
//     HashAlgorithm  ::=  AlgorithmIdentifier{DIGEST-ALGORITHM,
//                             {HashAlgorithms}}
//
//     HashAlgorithms DIGEST-ALGORITHM ::=  {
//         { IDENTIFIER id-sha1 PARAMS TYPE NULL ARE preferredPresent } |
//         { IDENTIFIER id-sha224 PARAMS TYPE NULL ARE preferredPresent } |
//         { IDENTIFIER id-sha256 PARAMS TYPE NULL ARE preferredPresent } |
//         { IDENTIFIER id-sha384 PARAMS TYPE NULL ARE preferredPresent } |
//         { IDENTIFIER id-sha512 PARAMS TYPE NULL ARE preferredPresent }
//     }
WARN_UNUSED_RESULT bool ParseHashAlgorithm(const der::Input input,
    DigestAlgorithm* out);

// Base class for describing algorithm parameters.
class NET_EXPORT SignatureAlgorithmParameters {
public:
    SignatureAlgorithmParameters() { }
    virtual ~SignatureAlgorithmParameters() {};

private:
    DISALLOW_COPY_AND_ASSIGN(SignatureAlgorithmParameters);
};

// Parameters for an RSASSA-PSS signature algorithm.
//
// The trailer is assumed to be 1 and the mask generation algorithm to be MGF1,
// as that is all that is implemented, and any other values while parsing the
// AlgorithmIdentifier will thus be rejected.
class NET_EXPORT RsaPssParameters : public SignatureAlgorithmParameters {
public:
    RsaPssParameters(DigestAlgorithm mgf1_hash, uint32_t salt_length);

    DigestAlgorithm mgf1_hash() const { return mgf1_hash_; }
    uint32_t salt_length() const { return salt_length_; }

private:
    const DigestAlgorithm mgf1_hash_;
    const uint32_t salt_length_;
};

// SignatureAlgorithm describes a signature algorithm and its parameters. This
// corresponds to "AlgorithmIdentifier" from RFC 5280.
class NET_EXPORT SignatureAlgorithm {
public:
    ~SignatureAlgorithm();

    SignatureAlgorithmId algorithm() const { return algorithm_; }
    DigestAlgorithm digest() const { return digest_; }

    // Creates a SignatureAlgorithm by parsing a DER-encoded "AlgorithmIdentifier"
    // (RFC 5280). Returns nullptr on failure.
    static std::unique_ptr<SignatureAlgorithm> CreateFromDer(
        const der::Input& algorithm_identifier);

    // Creates a new SignatureAlgorithm with the given type and parameters.
    static std::unique_ptr<SignatureAlgorithm> CreateRsaPkcs1(
        DigestAlgorithm digest);
    static std::unique_ptr<SignatureAlgorithm> CreateEcdsa(
        DigestAlgorithm digest);
    static std::unique_ptr<SignatureAlgorithm> CreateRsaPss(
        DigestAlgorithm digest,
        DigestAlgorithm mgf1_hash,
        uint32_t salt_length);

    // The following methods retrieve the parameters for the signature algorithm.
    //
    // The correct parameters should be chosen based on the algorithm ID. For
    // instance a SignatureAlgorithm with |algorithm() == RsaPss| should retrieve
    // parameters via ParametersForRsaPss().
    //
    // The returned pointer is non-owned, and has the same lifetime as |this|.
    const RsaPssParameters* ParamsForRsaPss() const;

private:
    SignatureAlgorithm(SignatureAlgorithmId algorithm,
        DigestAlgorithm digest,
        std::unique_ptr<SignatureAlgorithmParameters> params);

    const SignatureAlgorithmId algorithm_;
    const DigestAlgorithm digest_;
    const std::unique_ptr<SignatureAlgorithmParameters> params_;

    DISALLOW_COPY_AND_ASSIGN(SignatureAlgorithm);
};

} // namespace net

#endif // NET_CERT_INTERNAL_SIGNATURE_ALGORITHM_H_
